Student&#39;s computer

ABSTRACT

This disclosure describes a novel computer system in which a large capacity, serial storage medium, on which standardized programs and data banks can be economically recorded, as the primary memory component. The operating software program is not transferred into core memory, as is typical of present day computers, but remains resident in the memory on which it has been prerecorded. The resulting system is lower in cost, and especially suitable for using standardized programs which can be distributed in machine compatible form at modest cost.

This application is a continuation-in-part of U.S. application Ser. No.375,455 filed July 2, 1973.

REFERENCES

The embodiments described in this disclosure employ, in part, subsystemsdescribed in the following references:

1. U.S. Pat. No. 3,755,792 issued August 28, 1973, entitled "DIGITALDATA STORAGE SYSTEM." Issued to Norman L. Harvey.

2. INTRODUCTION TO PROGRAMMING, Digital Equipment Corp. small computerhandbook series.

3. 8080 MICROCOMPUTER SYSTEM USER'S MANUAL, Intel Corporation, July,1975.

BRIEF SUMMARY OF THE INVENTION

My invention is of an improved computer architecture particularlysuitable for low cost, free standing equipment to be used in the schoolclassroom environment. It employs storage media which can beeconomically mass produced with pre-recorded programs and data files,which can be essentially "plugged in" to the equipment, and whichfunction as the primary operating memory component without the necessityof program transfer to internal core.

Although many schools are already using computers in the educationalprocess, there is a great need for equipment having the featuresdescribed in this disclosure. Present equipment is so costly that it isa rare school that can afford more than 6 or 8 terminals, and it isusually necessary to concentrate these terminals in a computer room towhich students come, rather than taking the terminals into the classroomitself. Present systems further require a level of training on the partof the general classroom teacher that most are unwilling or feel unableto absorb.

My invention overcomes these limitations of existing systems, achievingsubstantially lower cost and greatyly increased teacher convenience byemploying as the primary operating memory of the computer a low cost,mass producible, storage medium on which programs and data arepre-recorded, and which can be easily plugged in to the computer. Thenormal core memory, as a result, can be very small since it is neededonly to receive operator-entered data, to store the intermediate resultsof calculations, and to store certain program subroutines.

In a preferred embodiment of my invention, a vinyl phonograph disk isused as this storage medium. Phonograph disks can be replicated in largevolume by conventional record pressing techniques, can be distributed atcosts approximating those for printed materials, and are easily "pluggedin" to the equipment. An efficient method of recording digital data onphonograph disks, and of recovering it, is described in my U.S. Pat. No.3,755,792. The use of a magnetic tape cassette also is described.

The customary input/output devices can be employed, but the phonographdisk and the tape cassette both permit the use of prerecorded voicemessages as a novel and economical feature. Means to utilize thiscapability is disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more apparent by reference to the followingdrawings which show certain preferred embodiments of the invention:

FIG. 1 is a general assembly view of an embodiment employing aphonograph-type disk as the plug-in memory component, a simple decimalkeyboard entry device, and a small visual display and audio headphoneoutput means.

FIG. 2 is a functional block schematic showing the elements of myinvention integrated into a typical mini-computer;

FIG. 3 is a side elevation, sectioned along lines 3--3 of FIG. 1,showing the cartridge carriage assembly;

FIG. 4 is a front elevation of the cartridge and its holder showingmeans for lifting the stylus from the disk;

FIG. 5 is an enlarged plan view illustrating the arrangement for lockingthe carriage at a selected position to engage the grooves carrying aparticular stored program;

FIG. 6 is a block schematic of the complete system implemented withstandard components of the Intel Corporation microprocessor line; and

FIG. 7 shows the detailed circuit interfacing the phonograph disk memorysystem and the voice message system to the microprocessor.

DETAILED DESCRIPTION

Referring first to FIG. 1, the computer, employing a phonograph-typedisk in this preferred embodiment, is shown assembled in a case 1. Disk2 is centered over post 3 on a turntable 4 which rotates typically at 45rpm, although other rotation speeds may be used if advantageous tocertain applications. A small motor 5 with a pulley 6 secured to itsshaft 7 drives the turntable 4 by means of a belt 8.

A rail 11 bridges across the top of the turntable and disk, and servesas a support and track for a cartridge carriage assembly which can bemoved along it to selected radial positions over the grooves of disk 2.Rail 11 is supported at either end by rail blocks 30 and 31, to which itis precisely located by taper pins 32 and 33, and fastened with capscrews 34 and 35.

The carriage assembly consists of plate 12 to which is fastened railguide 13 by means of machine screws not visible in this figure. Firmlyfixed to rail guide 13 by machine screws 14 and 15 is a lever base 10which carries a fixed lever 16, and blocks 17 and 18 between whichcarriage release lever 19 can turn about a small shaft 20. A compressionspring 21 holds the levers 16 and 19 normally apart. The teacher orstudent can free the cartridge assembly to move along rail 11 simply bypinching together levers 16 and 19.

Mounted also on plate 12 of the carriage assembly is cup solenoid 25with its armature 26, and pivot 27, about which the cartridge armassembly, underneath and not visible in this plan view, can turn.

The teacher (or student) prepares to use the computer by selecting adisk carrying the pre-recorded program he desires, and placing it on theturntable. He next pinches together levers 16 and 19, and moves thecartridge assembly along the rail to position the stylus over thelead-in groove to the particular program he wants to use. When thelevers are released, a knife edge on the lower part of lever 19 engagesserrations 94 in rail 11 (see FIG. 5) and locks the assembly in place.

In this embodiment the student enters coded commands and numbers intothe computer by means of a ten digit keyboard 40. Computer output is bymeans of a numeric display 41, and aurally by headphones plugged intophone jack 44.

The computer is turned on by line switch 42, and the "ON" condition isindicated by pilot light 43.

FIG. 2 is presented to show the altered functional relationships amongthe elements of a typical mini-computer system when the plug-in memoryis introduced into the system. It is intended more to show thefunctional relationships within the processor, than as a functionaldesign of the improved system.

To one skilled in the art, most of the component parts of the blockschematic of FIG. 2 will be recognized as a typical mini-computer. (e.g.see FIG. 2-l, page 2-5 of Introduction to Programming, Digital EquipmentCorporation). Input is made to the computer by conventional keyboard 60with the binary coded key-strokes accumulated in accumulator 52. Anycarries out of the accumulator in the course of the performance ofarithmetic operations, set link 65. Computer output is to display 64from accumulator 52 in a well known manner.

Transfers of data and instructions, both input and output, betweenaccumulator 52 and random access memory 61 are routed through a memorybuffer register 62. Instructions from the program software are movedfrom random access memory 61, through memory buffer register 62, toinstruction register 54 from which they direct the selection of thehard-wired instructions from the instruction set of the system. With theexecution of each instruction, sub-program counter 63 is supplied withthe address of the next instruction to be executed. Memory addressesreferenced by an instruction are held in memory address register 57.

The inter-functioning of all these elements of FIG. 2 just described, isentirely in a well known and conventional manner when used inconjunction with the additional components comprising the system of myinvention, and is fully described in any book on mini-computerarchitecture. To this conventional system, I have added certainadditional components in a novel manner, and these will be describedmore fully in connection with FIGS. 2, 6, and 7.

The crucial addition, continuing with FIG. 2, is dynamic serial memory50. In a first preferred embodiment of my invention, dynamic serialmemory 50 is a phonograph-type disk encoded with software and data indigital form. In an alternative embodiment of my invention, magnetictapeis employed as the dynamic serial memory. The word "dynamic" is usedhere to describe the fact that these two alternative storage media arein motion as used in my computer system.

In the preferred embodiment employing the phonograph-type disk, a numberof appropriate computer programs useful to the classroom are encoded inthe spiral groove of the disk in machine language form. Any one ofseveral known techniques for recording digital data on a phonograph diskmay be employed, but the method described in my U.S. Pat. No. 3,755,455is especially efficient and suitable. Using that method, data can bestored readily at densities of 2000 bits per linear groove inch. Theinnermost groove may have, typically, a diameter of 31/2 inches, orabout 11 inches of groove length for one revolution. The storagecapacity of this groove is then 11 × 2000 bits, or 22,000 bits total. Ifthe computer is designed to use an 8 bit word, this groove provides acapacity of about 2750 such 8 bit words. The other grooves, in a systememploying a constant speed turntable, can store the same amount ofsoftware at lower density.

If magnetic tape is used for dynamic serial memory 50, the programs anddata can be stored in the same complementary pair of tracks as describedin my previously referenced patent, in the self clocking Manchestercode, or in other suitable form. The tape is most conveniently handledif it is used in cassette form. A conservative recording density of 1000bits per inch, will require 22 inches of tape to provide the samestorage capacity as available in one turn of the disk as describedabove.

In the conceptual schematic of FIG. 2, the data is recovered from thedisk as described in my U.S. Pat. No. 3,755,455 as a serial data stream.Then 8 bit groups are assembled in a second memory buffer register 51.From there data is separated out and routed to accumulator 52, andthence either to display 64, or through memory buffer register 62 torandom access memory 61. Most importantly, however, a series of programinstructions increment program counter 53 and are transferred toinstruction register 54 for execution. The tempo and the sequence ofprocessing steps executed by the computer system is established by the8-bit words being output by the dynamic serial memory 50, and not by anyprogram stored in the random access memory 54. Unlike existing systemswhere programs are transferred from external storage devices, likemagnetic tape cassettes, into an internal random access memory, and thenexecuted by progressively stepping through the internally storedprogram, the system of my invention retains the mass storage device asthe operating source of the program being executed. The internal randomaccess memory is used only as a "scratch pad," or to hold relativelyshort subroutines.

Since the program is stored and output in sequential form, any programwhich requires looping back to an earlier portion of the program employslooping control 58. In that case an earlier address would be transferredfrom program counter 53 to memory address register 57, identified asrequiring looping by instruction register 54, and activate loopingcontrol 58. Cup solenoid 25 is de-energized, Hook 82 (See FIG. 3) raisesarm 76 with cartridge 72, and disengages stylus 73 from the groove. Bymeans to be described in detail in the discussion of FIGS. 3 and 4, thestylus is repositioned to the portion of the groove in which the startof this particular program resides.

Retaining program control in a storage medium such as a tape cassette ora phonograph disk, makes it feasable to store audio messages integralwith the program. This is shown as a voice message storage 55 in FIG. 2,actually an integral part of dynamic serial memory 50. The voice isrecorded on tape or disk in a conventional manner. Under programcontrol, these messages are output through voice output 56, which for aclassroom could be an amplifier and either speaker or headphones.

FIG. 6 shows an embodiment of a system utilizing my invention in furtherdetail as implemented using the micro-processor and related chipcomponents manufactured by Intel Corporation. Complete detail of theinterconnection of the Intel components among themselves, and betweenthem and standard I/O devices, is provided in their "8080 MicrocomputerSystems User's Manual," July 1975. The full detail of theinterconnection to the nonconventional components required to utilize myinvention, is provided in connection with FIG. 7.

Referring now to FIG. 6, the Intel 8080A Central Processing Unit, withit's 47 instruction set is shown as 101. An Intel 8224 Clock 102,controlled by crystal 103, provides 2-phase clock signals to CPU 101.Ready, Reset, and Sync connections are provided between the units asdescribed in the User's Manual. An Intel 8228 bi-directional Bus Driverand Control 104 interfaces CPU 101 to an 8-line data bus 106, and to a5-line control bus 107. Data can flow in either direction between the8080A CPU and the 8228 Bus Driver through data bus 105. A request fromany peripheral device that the CPU 101 enter a "hold" state isacknowledged on the HLDA line. The DBIN line carries a signal toperipheral devices through the control bus that the data bus is in theinput mode, and a signal on the WR line indicates an ouput write to aperipheral. An STSTB (strobe) input from Clock 102 strobes instructionstatus information onto the data bus at the beginning of eachinstruction cycle.

Intel 8212 I/O Ports 109 through 114 are shown interfacing several I/Odevices to control bus 107 and data bus 106. An address bus 108 connectsdirectly from CPU 101 to the several 8212 Ports. The address bus carriesI/O device addresses and device identification information. An Intel8102A random access memory 115 is connected to Port 109 to serve as ascratch pad memory, including the storing of short program subroutines.The Port 115 provides an 8-bit latch and output buffering. A read-onlymemory chip, the Intel 8702A 116 is interfaced to the system throughPort 112 to provide a storage for standard utility software, such as akeyboard monitor.

Keyboard 117 is conventional, as is its connection to the system throughPort 110. The keyboard can be the simple 10-digit keyboard 40 shown inFIG. 1, or a standard teletype keyboard. Display 118 is the conventionalset of drivers and light emitting diodes, and is connected to the systemthrough Port 113 in a manner well known to those skilled in the art.

A vinyl disk 119, connected through Port 111, is the source of programand data to be executed and utilized by the system. A magnetic tape unit120 is shown in dashed lines as an alternate source of program and data.Optional magnetic tape 120 is interfaced to the system through Port 114.A voice output unit, 121, comprising an audio amplifier and headset, isactuated under program control through control bus 107.

In FIG. 7 the details of the interconnection of those portions of thesystem wherein the novelty lies, are shown. Vinyl disk 125, in thisembodiment, is considered to be encoded with non return to zero--changeat one (NRZ1) signals in one track of a stereo pair, and with thecomplementary non return to zero--change at zero (NRZO) signal in theother, as described in detail in my U.S. Pat. No. 3,755,455. As furtherdescribed in that patent, each of the two signals is recoveredindependently with a stereo cartridge, amplified and shaped in separatechannels, and output as a compleementary pair of pulse trains. Amplifier& shaping circuits 126 perform these functions according to the teachingof that patent.

The signals encoded on vinyl disk 125 are encoded as a sequential streamof 1's and 0's, each group of 8 representing one data word. In thecomplementary channel, 1's replace 0's, and 0's replace the 1's. In FIG.7, the B channel is shown as the direct channel, and the A channel asthe complementary one. In order to distinguish whether each data wordoutput from the disk is an instruction, data, or an address, some formof coding is necessary. One efficient method, available because of theexistence of a complementary pair, is to break the complementaryrelationship for one 8-bit data word as a synchronizing signal. Theparticular arrangement depicted in FIG. 7 is based upon encoding 1's inboth channels for one full 8-bit word to indicate that the next 8-bitword will be an address, and that all succeeding words are to be assumedto be either data or instructions located in an ascending sequence ofaddresses. In other words, any full sequence of 8-bits in both channelsis a synchronizing signal only. The next 8-bit word is an address, andeach following 8-bit word is to be considered as located in memory at anaddress incremented by one over the next previous address. Thiscontinues until the next synchronizing word is output.

Turning again to FIG. 7, the train of pulses output on the B channelfrom amplifier and shaping circuits 126 branches into three paths. Thelower one of the three paths in the schematic leads to an 8-bit serialregister 128 where the 8-bit data words are assembled. Register 128 isalso connected in parallel to the eight latches of the Intel 8212 I/Oport 111. The latches are set when port 111 is strobed at the STRconnection.

Asecond branch of the B-channel output from amplifier and shapingcircuits 126 leads to Inclusive OR gate 129. One branch of the A channelalso leads to OR gate 129, and the gate output, which is an unbrokenstream of 1's, is used to synchronize clock 130 at the bit rate outputfrom the disk. One output from clock 130 is used to sequence serialregister 128. As bits are sequenced out of the high end of the register,they are dissipated in the resistor load 131.

The A and B channels are ANDed in gate 127, the output of which isdivided by 8 in divider 132. A second output from clock 130 is dividedby 8 in a second divider 134. One output from this divider provides thestrobe signal to I/O port 111, a second clears divider 132, and a thirdis input to AND gate 133, along with an output from divider 132. Anoutput from gate 133 is lead to the interrupt (INT) terminal of I/O port111, and transmitted to the CPU 101 over the control bus. The completionof the transfer of a data word from I/O port 111 to CPU 101 isacknowledged with a clear (CLR) signal back to the I/O port which clearsthe latches.

The first word in each program on vinyl disk 126 is a synchronizingword, i.e. 8 successive bits in both A and B channels. Clock 130, anddividers 132 and 134 will all be initialized simultaneously, and at theeighth bit, there will be a bit appearing simultaneously on both inputports of AND gate 133. These will AND to produce an interrupt to the CPU101, a clear signal will be returned to I/O port 111, the latches of theport will be cleared, and the system is ready to receive the firstaddress word. This normally will be the address of initialization of theprogram counter in CPU 101, and the ensuing words will be instructions.

CPU 101 increments its program counter after executing each instruction,and sends out an address on the address bus with a request for theinformation stored at that location. The vinyl disk outputs a data wordthat is at an address defined as being the next higher address, and thecomputing process proceeds. If data is to be transferred, a synch signalis output, a new address sequence is started at a memory locationassigned to data, and data is transferred and processed under programcontrol. At the conclusion of data transfer, another synch word caninitiate a return to addresses assigned to instructions. The ROM 116 canbe accessed for general service routines in a conventional manner, andthe RAM 115 can be used dynamically as a scratch pad for short specialroutines and for holding processing results.

Small loops can be read from vinyl disk system into the RAM and executedas subroutines. A major loop can be identified in the stored program asa previously used address, initiating a hold request to the CPU, andactivating via the control bus an initiating signal to latch 135, thusinitiating switching action by transistor 136 to solenoid 25. The stylusis raised and mechanically repositioned to the starting groove, lowered,the system is re-initialized for synchronization, and a search isinstituted for the desired address, all under software control.

Vinyl disk 125 also can be encoded with audio messages, recorded eithermonaurally or in stereo by normal recording techniques, and interspersedwith the digital data on the disk. These messages would be brief programresponses or promptings to the student, requiring a playing time of theorder of one second. Each response is preceeded by a synch signal and aunique address. In program execution, an instruction will call for aninput from that memory address, a service routine stored in ROM 116 willidentify that address as a disk audio location, a control signal will betransmitted via the control bus to enable (ENL) audio amplifier 140. Thesame cartridge and stylus associated with disk 125 which recovers thestored digital data, also recovers the audio message which is input by asecond circuit connection to audio amplifier 140. The amplifier outputactuates a small loudspeaker 141. It is obvious that headphones can besubstituted for the loud speaker. At the conclusion of the voicemessage, another synch signal initiates an interrupt to CPU 101 as waspreviously.

It is well known that magnetic tape and phonograph disks have comparablecapabilities of frequency range, signal to noise ratio, and generalrecording fidelity in the recording of sound, and both media are usedextensively commercially for this purpose. Moreover, the use of magnetictape for the storage of digital data is extensive and well known. Itwill accordingly be obvious to those skilled in the art, that a magnetictape cassette could readily be substituted for vinyl disk 125 in asecond alternative embodiment of my invention. Digital data, in directand complementary form can be recorded on two tracks of such a magnetictape storage component, and these two outputs can be input to amplifierand shaping circuits 126 in exactly the same manner as has beendescribed for signals from the vinyl desk. Other encoding means can beused for the magnetic tape, suchas single track with the so-calledManchester code, by making modifications to the circuits for otherpatterns of timing and sychronizing signals. Such modifications will bereadily made by those skilled in the art.

Looping requirements in using a magnetic tape cassette are met by usingtransistor switch 136 to activate a rewind to a beginning-of-file markencoded on the tape. This rewind operation replaces sequence of liftingand repositioning the stylus when using the phonograph-type disk.

FIG. 3 shows, in a view sectioned along lin 3--3 of FIG. 1, details ofthe cartridge carriage assembly, . . It is this assembly that thestudent moves along rail 11 as he selects the particular program hewants to use. The parts of the carriage assembly are mounted mostly onplate 12. Rail guide 13, machined to provide a smooth sliding fit torail 11, is fastened to plate 12 by small machine screws 70 and 71.Fastened, in turn, to rail guide 13 by means of screws 14 and 15 (only15 is visible in this figure), is lever base 10, to which fixed lever 16is firmly attached. Carriage release lever 19 rotates about shaft 20,which is supported between a pair of blocks, of which one, 18, isvisible in FIG. 3. Compression spring 21 holds the two levers 16 and 19apart.

Cartridge 72 with its stylus 73 is held in cartridge arm 76 by springclips 74 and 75. Arm 76 is fastened to a small bearing block 77 whichpivots around pin 78, which is held in yoke 79. This pivotingarrangement permits the cartridge 72 to move in a vertical arc. Yoke 79,in turn, can turn about the vertical axis provided by shoulder pin 27which is mounted in plate 12. Arm 76 is unusually short as compared totypical phonograph tone arms. This short arm is practical because themaximum travel of stylus 73 along the disk radius during programexecution is only a few grooves of the spiral, spanning perhaps 1/32inch. The angular travel is thus an order of magnitude less than thatrequired in normal audio record players, and approaches much moreclosely the ideal of having no lateral component in the tracking force.

The stylus is raised by hook 82 which engages a triangular opening incartridge arm 76. The triangular opening has its apex at the top, and iswide enough in the lower portion so that when stylus 73 has been loweredinto the groove, it can move laterally through at least the full 1/32inch allocated to one program without hook 82 coming into contact withthe sides of the triangular opening. When hook 82 is raised so as tolift the stylus clear of the disk groove, it then comes into contactwith both sides of the triangular opening as it nears the apex, and soreturns the cartridge arm 76 and stylus 73 to the position that thestudent had set initially. This operation occurs every time loopingcontrol 58 of FIG. 2 is activated in introducing a pause in programexecution of student response, or for looping back to earlier portionsof the program on the disk.

Hook 82 is an integral part of armature 26 of cup solenoid 25. In thede-energized condition of solenoid 25, the armature 26 is held in araised position by compression spring 83, pushing against iron washer84, which is held onto armature 26 by locking pin 85. The normallyraised position of stylus 73 is a safeguard against stylus of diskdamage when the computer is being moved.

FIG. 4 is a front end view of the cartridge and its lifting means,intended to further clarify the arrangement of the triangular opening.Cartridge 72 is shown with stylus 73 just leaving engagement with agroove on disk 2. Cartridge 72 is held to cartridge arm 76 by springclips 75. The triangular opening 89 in the forward portion of arm 72 isshown, with a section view of hook 82 engaged at the apex of thetriangular opening.

FIG. 5 shows the manner in which the cartridge carriage assembly islocked to a selected program position by a knife edge in the lowerportion of release lever 19 engaging accurately milled serrations 94 inrail 11. In this illustrative embodiment, serrations 94 are 1/32 inchescenter-to-center, and are positioned to register with the mid-point of alead-in spiral groove for each recorded program on the disk. Aset ofcalibration marks 92 is engraved on rail 11, and are also in registrywith corresponding serrations 94, so that one edge of plate 12 serves asan index for reading the particular program setting of the carriageassembly. In FIG. 5 the carriage is shown positioned at Program #12. Aposition "X" is shown at 93 that is used to position the carriage out ofthe way when replacing a disk on the turntable. Other parts in theFigure are as identified and explained in connection with theexplanation of previous figures in this specification.

It will be apparent that other input and output devices can be used insystems utilizing my invention. For example, a standard alpha-numerickeyboard can be used in place of the simple ten-digit keyboard. Outputalso can be made to an alpha-numeric LED display, to electrictypewriter, to graphical platting devices, or to a cathode ray tube.

It will be understood that many of the specific means described for thepreferred embodiments disclosed in this specification, may be replacedor modified, and still will be within the scope of my invention.

What is claimed is:
 1. A data processing apparatus, comprising:a plasticdisk on at least one face of which a sequentially organized combinationof synchronization signals, processor instructions, and related data hasbeen stored as undulations in aspiral groove; transducer means fortransforming the undulations into an electrical signal having acorresponding pattern of pulses; detection means for identifying certainpulse patterns as said synchronization signals, each occurrence of whichrepresenting a predetermined reference point in the organized sequenceof said instructions and data; clocking means synchronized to saidpattern of pulses; serial register means responsive to said clockingmeans and said detection means for assembling subsequent portions ofsaid pattern of pulses into binary words; decoding means for identifyingwhich portions of said pulse patterns represent addresses, processorinstructions, digital data, or data in other forms; data processor meansfor performing data processing operations; first interfacing meansresponsive to said decoding means for selectively transferring eachassembled binary word which represents a processor instruction from saidserial register means to said data processor means; second interfacingmeans responsive to said decoding means and said processor means forselectively transferring each subsequently assembled binary word,representing the data related to said transferred instruction, from saidserial register means to said data processor means; said data processormeans performing the operations indicated by each said instruction uponits related data immediately upon completion of the respective transfersby said first and second interfacing means; and output means forreporting the results of the operations performed on said transferreddata.
 2. The data processing apparatus of claim 1 wherein means areincluded to disengage said sensing means from the spiral groove, returnit to a preceeding portion of said groove, and to reengage it in thegroove so as to recycle through a portion of the stored data andprocessor instructions.
 3. The apparatus of claim 1 wherein said plasticdisk is a phonograph type disk encoded with data and processorinstructions.
 4. The apparatus of claim 1 wherein said plastic diskstores both voice messages and data encoded in digital form.
 5. Theapparatus of claim 1 wherein said plastic disk is readily replacable bythe user with a similar disk on which a second series of data andprocessor instructions has been stored.